JP7407121B2 - Carbon hard masks and related methods for patterning applications - Google Patents

Description

[0001] Embodiments described herein generally relate to the field of semiconductor device manufacturing, and more particularly, to amorphous carbon layers used in electronic device manufacturing processes and methods of depositing amorphous carbon layers.

[0002] A carbon hard mask formed from amorphous carbon is used when forming a high aspect ratio opening (for example, a height to width ratio of 2:1 or more) on the surface of a substrate or in the surface layer of the material. Used as an etching mask in semiconductor device manufacturing. In general, the processing challenges associated with forming high aspect ratio openings include clogging, hole shape distortion, pattern deformation, maximum critical dimension expansion, line bending, and profile bowing. This is a result of undesirable material properties of conventionally deposited carbon hard masks. For example, a carbon hardmask with one or a combination of a lower material density and a lower material stiffness (i.e., Young's modulus) will have a higher It is known to cause increased deformation of the aspect ratio opening. Similarly, both the lower etch selectivity between the hardmask material and the underlying substrate material to be etched, and the hardmask material having higher film stress (compressive or tensile), is known to cause increased slit pattern distortion and line bending when compared to processes using hardmask materials with higher etch selectivity to substrate materials and lower film stress. Furthermore, as the critical dimension (CD) shrinks and the height of the high aspect ratio aperture increases, the thickness of the conventionally deposited carbon hardmask used to form the high aspect ratio aperture increases. It also increases. Unfortunately, hardmasks with lower transparency can cause alignment problems in subsequent photolithography processes due to lower optical K and/or increased thickness. Hardmask materials that have higher etch selectivity to the underlying substrate material enable thickness reductions and are therefore desirable compared to hardmasks that have lower etch selectivity. Additionally, processes with lower etch selectivity between the hardmask material and the underlying substrate material often rely on relatively thicker hardmasks, which undesirably reduce processing time and deposition This increases costs, leading to reduced substrate throughput and increased device costs.

[0003] Accordingly, there is a need in the art for improved amorphous carbon hardmasks and improved methods of forming amorphous carbon hardmasks.

[0004] Embodiments of the present disclosure generally employ a plasma enhanced chemical vapor deposition (PECVD) process and a hard mask formed therefrom to deposit an amorphous layer on a substrate, including over previously formed layers on the substrate. A method for depositing a carbon layer will be explained.

[0005] In one embodiment, a method of processing a substrate includes placing the substrate on a substrate support, the substrate support being disposed within a processing space of a processing chamber. flowing a process gas including a hydrocarbon gas and a diluent gas into the process space; maintaining the process space at a process pressure of less than about 100 mTorr; and applying the first electrical power to one or more of the process chambers. igniting and maintaining a deposition plasma of a process gas by applying a power source to one of the electrodes of the substrate, maintaining the substrate support at a process temperature of less than about 350 degrees Celsius, and applying a power supply to the surface of the substrate in the deposition plasma. exposing and depositing an amorphous carbon layer on the surface of the substrate.

[0006] In another embodiment, a method of processing a substrate includes placing the substrate on a substrate support, the substrate support being disposed within a processing space of a processing chamber. disposing the first alternating current power on the substrate support, flowing a process gas including a hydrocarbon gas and a diluent gas into the process space, maintaining the process space at a process pressure of less than about 20 mTorr; igniting and maintaining a deposition plasma of a process gas by applying a first alternating current power to one of the one or more power electrodes of the substrate support, the first alternating current power being applied to one of the one or more power electrodes of the substrate support; igniting and maintaining a deposition plasma of a processing gas of between about 0.7 watts and about 15 watts; maintaining the substrate support at a processing temperature of less than about 100 degrees Celsius; and subjecting a surface of the substrate to the deposition plasma. exposing and depositing an amorphous carbon layer on the surface of the substrate.

[0007] In another embodiment, the carbon hard mask includes an amorphous carbon layer disposed on a surface of the substrate, wherein the amorphous carbon layer is a young amorphous carbon layer having a density of greater than about 1.8 g/cm ³ and a density of greater than about 50 GPa. index, a film stress of less than about 500 MPa, and an absorption coefficient (optical K) of less than about 0.15 at a wavelength of about 633 nm.

[0008] In order that the features of the disclosure described above may be understood in detail, the disclosure summarized above will now be described more specifically with reference to embodiments, some of which are illustrated in the accompanying drawings. It should be understood, however, that the accompanying drawings illustrate only typical embodiments of this disclosure and therefore should not be considered limiting, as this disclosure may also tolerate other equally valid embodiments. Please note.

[0009] FIG. 1 is a schematic cross-sectional view of an exemplary processing chamber used to perform the methods described herein, according to one embodiment. [0010] FIG. 2 is a flow diagram of a method of depositing an amorphous carbon layer, according to one embodiment. [0011] FIG. 3 illustrates a carbon hard mask formed from an amorphous carbon layer deposited according to the method described in FIG. 2, according to one embodiment.

[0012] Embodiments of the present disclosure generally provide methods for depositing an amorphous carbon layer on a substrate, including over previously formed layers on the substrate, using a plasma enhanced chemical vapor deposition (PECVD) process. Explain how. In particular, the methods described herein utilize lower processing pressures, e.g., less than about 100 mTorr, lower processing temperatures, e.g., less than about 350 degrees Celsius, than are typically used in conventional methods of depositing amorphous carbon layers. , and higher power, such as greater than about 1000W. In some embodiments herein, the electrical power used to ignite and maintain the deposition plasma is provided by one or more power sources disposed within or connected to the substrate support on which the substrate is disposed. supplied to the electrodes. Each or a combination of lower process pressure, lower process temperature, higher power, and substrate level plasma (plasma generated through capacitive coupling with a power electrode of the substrate support) may be used during deposition. increases the ion energy at the substrate surface and produces an amorphous carbon layer with a desirably higher ratio of sp3 content (diamond-like carbon) to sp2 content (graphitic carbon) when compared to conventional deposition methods. bring. Because of the resulting higher sp3 content, the method described herein provides improved density, stiffness, transparency, and etch selectivity when compared to conventionally deposited amorphous carbon layers. , and an amorphous carbon layer having film stress.

[0013] FIG. 1 is a schematic cross-sectional view of an exemplary processing chamber used to perform the methods described herein, according to one embodiment. Other exemplary deposition chambers that may be used to carry out the methods described herein include Radion®, Producer, available from Applied Materials, Inc., Santa Clara, Calif. and SYM3® processing chambers, as well as suitable deposition chambers from other manufacturers.

[0014] Processing chamber 100 includes a chamber lid assembly 101, one or more sidewalls 102, and a chamber base 104. Chamber lid assembly 101 includes a chamber lid 106, a showerhead 107 disposed within chamber lid 106, and an electrically insulating ring 108 disposed between chamber lid 106 and one or more sidewalls 102. Showerhead 107 , one or more sidewalls 102 , and chamber base 104 together define a processing space 105 . A gas inlet 109 disposed through chamber lid 106 is fluidly coupled to a gas source 110. Showerhead 107 has a plurality of openings 111 disposed therethrough and is used to uniformly distribute process gas from gas source 110 into process space 105 . Here, chamber lid assembly 101, and thus showerhead 107, is electrically connected to earthen ground. In other embodiments, the chamber lid assembly 101, and thus the showerhead 107 disposed therein, provides one or more bias voltages therein, such as a continuous wave (CW) RF power source, a pulsed RF power source, a DC power source, Electrically connected to a power source (not shown), such as a pulsed DC power source, or a combination thereof. In other embodiments, processing chamber 100 does not include a showerhead 107 and processing gases are supplied to processing space 105 through one or more gas inlets disposed through chamber lid 106 or one or more sidewalls 102. Ru.

[0015] Here, the processing space 105 is fluidly coupled to a vacuum source, such as one or more dedicated vacuum (when not in the sense of an absolute vacuum) pump, via a vacuum (when not in the sense of an absolute vacuum) outlet 114. , which maintains the processing space 105 at subatmospheric pressure and evacuates process gases and other gases therefrom. A substrate support 115 disposed within the processing space 105 is a movable support extending sealingly through the chamber base 104 such that it is surrounded by a bellows (not shown) in the region below the chamber base 104. located on the body shaft 116. Here, the processing chamber 100 is connected to the substrate support 115 through an opening 118 in one of the one or more sidewalls 102, which is sealed with a door or valve (not shown) during substrate processing. The substrate 117 is configured to facilitate transportation of the substrate 117.

[0016] Typically, a substrate 117 disposed on a substrate support 115 includes one of a heater, such as a resistive heating element 119, and one or more cooling channels 120 disposed within the substrate support 115. or both are used to maintain the desired processing temperature. One or more cooling channels 120 are fluidly coupled to a coolant source (not shown), such as a water source or a coolant source that has been modified to have a relatively high electrical resistance.

[0017] In some embodiments, one or more power supply electrodes (not shown) embedded within or connected to the dielectric material of the substrate support 115 connect the first It is connected to one or more RF (radio frequency) or other alternating current frequency power sources, such as a power source 121A and a second power source 121B. Here, the deposition plasma 123 is generated within the processing space by capacitively coupling the processing gas within the processing space 105 with one of the one or more power supply electrodes using AC power supplied thereto from the first power supply 121A. ignited and maintained. In some embodiments, the deposition plasma 123 is further maintained by capacitively coupling to one of the one or more power supply electrodes with alternating current power supplied thereto from the second power supply 121B. Here, the first power source 121A and the second power source 121B each supply AC power having a frequency between about 350 kHz and about 100 MHz, in which case, the frequency of the power from the first power source 121A is: The frequency is different from the frequency from the second power source 121B.

[0018] FIG. 2 is a flow diagram of a method of depositing an amorphous carbon layer on a surface of a substrate, according to one embodiment. At step 201, method 200 includes placing a substrate on a substrate support. Here, the substrate support is disposed within a processing volume of a processing chamber, such as processing chamber 100 illustrated in FIG. At step 202, method 200 includes flowing a process gas into a process space. Typically, the process gas is _a carbon source gas such as _a hydrocarbon gas, e.g. _CH4 , _{C2H2 , C3H8 , C4H10 , C2H4} , _C3H6 , _C4 H ₈ and C ₅ H ₁₀ , or a combination thereof, and a diluent gas, such as an inert gas such as Ar, He, Ne, Kr, or Xe, or a combination thereof. In some embodiments, the diluent gas includes _N2 , _H2 , or a combination thereof. In some embodiments, the hydrocarbon gas to diluent gas flow ratio (ratio) is between about 1:10 and about 10:1, such as between about 1:5 and about 5:1. . For example, in one embodiment, the ratio of C ₂ H ₂ to He is between about 1:3 and about 3:1. In some embodiments, the diluent gas comprises H ₂ and the ratio between H ₂ and the carbon source gas is between about 0.5:1 and about 1:10, such as between about 1:1 and about 1. :5. In step 203, the method 200 performs a method of generating an electric current between about 0.1 mTorr and about 100 mTorr, such as between about 0.1 mTorr and about 50 mTorr, between about 0.1 mTorr and about 30 mTorr, between about 0.1 mTorr and about 20 mTorr, about Maintaining the processing space at a processing pressure between 0.1 mTorr and about 15 mTorr, such as between about 0.1 mTorr and about 10 mTorr, or less than about 100 mTorr, less than about 50 mTorr, less than about 20 mTorr, less than about 15 mTorr, such as less than about 10 mTorr. Including.

[0019] At step 203, method 200 includes igniting and maintaining a deposition plasma of a processing gas by applying a first power to one of one or more power electrodes of the processing chamber. Herein, the one or more power electrodes include one or more top electrodes (e.g., a chamber lid of a processing chamber or a showerhead disposed within a chamber lid), one or more side electrodes (e.g., a or a portion of the substrate support (eg, one or more electrodes embedded within or connected to the dielectric material of the substrate support). Typically, the first power is between about 500 W and about 8 kW, such as between about 1000 W and about 5 kW, for a processing chamber sized to process a 300 mm diameter substrate. Appropriate scaling may be used for processing chambers sized to process substrates of different sizes.

[0020] In some embodiments, one or more power electrodes are one or a combination of embedded within or connected to the dielectric material of the substrate support. In some embodiments, for a substrate support having a substrate receiving surface sized to support a 300 mm diameter substrate, the first power is about Between 0.7 W and about 11.3 W (here W/cm ² ), such as between about 1.4 W/cm ² and about 7.1 W/cm ² , or between about 500 W and about 5 kW, such as about RF or other AC frequency power between 1000W and about 5kW.

[0021] In some embodiments, method 200 further includes applying a second power to one of the one or more power electrodes. In that case, the second power is about 0.14 W/cm ² and about 7.1 W/cm ² for a substrate support having a substrate receiving surface sized to support a 300 mm diameter substrate. at an RF or other AC frequency power of between about 0.14 W/cm ² and about 3.5 W/cm ² or between about 100 W and about 5 kW, such as between about 100 W and about 2.5 kW. be. Here, the frequency of the second power is different from the frequency of the first power. Typically, the frequency of one or both of the first power and the second power is between about 350 kHz and about 100 MHz, such as about 350 kHz, about 2 MHz, about 13.56 MHz, about 27 MHz, about 40 MHz. , about 60MHz, and about 100MHz. In some embodiments, the first power and the second power are applied to different power supply electrodes that are electrically isolated from each other. It is, for example, a double power electrode embedded in the dielectric material of the substrate support and insulated from each other by the dielectric material. In some embodiments, the first power and the second power are applied to the same power supply electrode using a conventional impedance matching circuit.

[0022] At step 204, the method 200 includes heating the substrate support, and thus the substrate disposed thereon, to a temperature between about -50 degrees Celsius and about 350 degrees Celsius, such as between about -50 degrees Celsius and about 150 degrees Celsius. between about -50 degrees Celsius and about 100 degrees Celsius, or between about -50 degrees Celsius and about 50 degrees Celsius, such as between about -25 degrees Celsius and about 25 degrees Celsius, or about 350 degrees Celsius. eg, less than about 200 degrees Celsius, less than about 150 degrees Celsius, or less than about 100 degrees Celsius, such as less than about 50 degrees Celsius.

[0023] In steps 205 and 206, method 200 includes exposing a surface of the substrate to a deposition plasma and depositing an amorphous carbon layer on the surface of the substrate, respectively.

[0024] FIG. 3 illustrates a carbon hard mask deposited according to the method described in FIG. 2, according to one embodiment. In FIG. 3, a carbon hard mask 303 (here, a patterned carbon hard mask) is disposed on the surface to be patterned of a substrate 300 and is an amorphous carbon layer having a plurality of openings 304 formed therein. 302 included. Typically, substrate 300 or one or more material layers thereof is crystalline silicon, silicon oxide, silicon oxynitride, silicon nitride, strained silicon, silicon germanium, tungsten, titanium nitride, doped or undoped polysilicon. , carbon-doped silicon oxide, silicon nitride, doped silicon, germanium, gallium arsenide, glass, sapphire, and low k dielectric materials.

[0025] Here, the amorphous carbon layer has a thickness of between about 1 kÅ and about 40 kÅ, such as between about 10 kÅ and about 40 kÅ, such as between about 10 kÅ and about 30 kÅ, and a density of more than about 1.8 g/cm ³ , a Young's modulus of greater than about 50 GPa, and an absorption coefficient (optical K) of less than about 0.15 at a wavelength of about 633 nm. In some embodiments, the amorphous carbon layer has a tensile or compressive membrane stress of less than about 500 MPa. In some embodiments, the amorphous carbon layer has a tensile membrane stress of less than about 500 MPa. In some embodiments, each of the plurality of apertures 304 is greater than about 2:1, such as greater than about 3:1, greater than about 4:1, greater than about 5:1, about 6:1. , greater than about 7:1, greater than about 8:1, greater than about 9:1, such as greater than about 10:1.

[0026] The methods described herein provide an amorphous carbon layer that has improved density, stiffness, transparency, etch selectivity, and stress when compared to conventionally deposited amorphous carbon layers. and a carbon hard mask formed therefrom. Additionally, it is desirable that the methods described herein be consistent with current carbon hardmask process integration schemes. That means that the introduction of the method into existing device manufacturing lines does not require substantial changes in upstream or downstream processing methods or the equipment associated therewith.

[0027] Although the above is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the essential scope of the present disclosure, and The scope is defined by the claims below.

Claims (28)

A method of processing a substrate, the method comprising:
placing a substrate on a substrate support disposed within a processing volume of a processing chamber;
flowing a processing gas including a hydrocarbon gas and a diluent gas into the processing space;
maintaining the processing space at a processing pressure of less than 100 mTorr;
igniting and maintaining a deposition plasma of the processing gas by applying a first electrical power to one of the one or more power electrodes of the processing chamber;
maintaining the substrate support at a processing temperature of less than 350 degrees Celsius;
exposing a surface of the substrate to the deposition plasma; and depositing an amorphous carbon layer on the surface of the substrate ;
A method , wherein the deposited amorphous carbon layer has a density greater than 1.8 g/cm ³ . 2. The method of claim 1, wherein the deposited amorphous carbon layer has a film stress of less than 500 MPa. 3. The method of claim 2, wherein the membrane stress is a tensile or compressive membrane stress. A method of processing a substrate, the method comprising:
placing a substrate on a substrate support disposed within a processing volume of a processing chamber;
flowing a processing gas including a hydrocarbon gas and a diluent gas into the processing space;
maintaining the processing space at a processing pressure of less than 100 mTorr;
igniting and maintaining a deposition plasma of the processing gas by applying a first electrical power to one of the one or more power electrodes of the processing chamber;
maintaining the substrate support at a processing temperature of less than 350 degrees Celsius;
exposing a surface of the substrate to the deposition plasma; and
depositing an amorphous carbon layer on the surface of the substrate;
A method, wherein the deposited amorphous carbon layer has a film stress of less than 500 MPa. 5. The method of claim 4, wherein the membrane stress is a tensile or compressive membrane stress. 6. A method according to any one of claims 1 to 5 , wherein the deposited amorphous carbon layer has a Young's modulus of more than 50 GPa. The deposited amorphous carbon layer has a wavelength of 0.5 nm at a wavelength of 633 nm. 7. A method according to any one of claims 1 to 6 , having an absorption coefficient (optical K) of less than 15. _The hydrocarbon gas is _CH4 , _C2H2 , _C3H8 , _C4H10 , _{C2H4 , C3H6 , C4H8} , _C5H10 , or _{a combination thereof .} 8. A method according to any one of claims 1 to 7, comprising one of : 9. A method according to any preceding claim , wherein the ratio of hydrocarbon gas to diluent gas is between 1:10 and 10 :1. The diluent gas is H ₂ and the H in the processing gas ₂ 9. A method according to any one of claims 1 to 8, wherein the ratio of to said hydrocarbon gas is between 0.5:1 and 1:10. 11. A method according to any one of claims 1 to 10 , wherein the treatment temperature is less than 100 degrees Celsius. 12. A method according to any one of claims 1 to 11 , wherein the processing pressure is less than 20 mTorr. 13. A method according to any preceding claim, wherein each of the one or more power electrodes is part of the substrate support. The first electrical power is 0.05 m/cm2 of the substrate receiving surface of the substrate support. 14. A method according to any one of claims 1 to 13 , wherein the first power is an alternating current power of between 7 W and 11.3 W , and the first power has a frequency between 350 kHz and 100 MHz. further comprising applying a second electrical power to one of the one or more power electrodes, the second electrical power being 0.000 volts per square centimeter of the substrate receiving surface of the substrate support. an alternating current power between 14 W and 7.1 W, the second power having a frequency between 350 kHz and 100 MHz, and the frequency of the first power being equal to the frequency of the second power. 15. The method of claim 14 , wherein the frequencies are different. A method of processing a substrate, the method comprising:
placing a substrate on a substrate support disposed within a processing volume of a processing chamber;
A processing gas containing a hydrocarbon gas and a diluent gas, wherein the hydrocarbon gas is CH _Four ,C ₂ H ₂ ,C ₃ H ₈ ,C _Four H _Ten ,C ₂ H _Four ,C ₃ H ₆ ,C _Four H ₈ ,C _Five H _Ten or a combination thereof into the processing space;
maintaining the processing space at a processing pressure of less than 20 mTorr;
igniting and maintaining a deposition plasma of the processing gas by applying a first electrical power to one of the one or more power electrodes of the processing chamber, each of the one or more power electrodes part of the substrate support, the first power being between 0.7 and 11.3 W of alternating current power per square centimeter of the substrate receiving surface of the substrate support; igniting and maintaining a deposition plasma of said process gas having a frequency between 350 kHz and 100 MHz;
applying a second power to one of the one or more power electrodes, the second power being between 0.14 W and 7.1 W per square centimeter of the substrate receiving surface of the substrate support; and the second power has a frequency between 350 kHz and 100 MHz, and the frequency of the first power is different from the frequency of the second power. applying a second power;
maintaining the substrate support at a processing temperature of less than 100 degrees Celsius;
exposing a surface of the substrate to the deposition plasma; and
A method comprising depositing an amorphous carbon layer on the surface of the substrate. A method of processing a substrate, the method comprising:
placing a substrate on a substrate support disposed within a processing volume of a processing chamber;
flowing a processing gas including a hydrocarbon gas and a diluent gas into the processing space;
maintaining the processing space at a processing pressure of less than 20 mTorr;
igniting and maintaining the process gas deposition plasma by applying a first alternating current power to one of the one or more power electrodes of the substrate support, wherein the first alternating current power is , 0.000000000000000000000000000 per square centimeter of substrate receiving surface of said substrate support. igniting and maintaining a deposition plasma of the process gas between 7 and 15 Watts;
maintaining the substrate support at a processing temperature of less than 100 degrees Celsius;
exposing a surface of the substrate to the deposition plasma; and depositing an amorphous carbon layer on the surface of the substrate ;
The method , wherein the diluent gas comprises H ₂ and the ratio of the H ₂ to the hydrocarbon gas in the process gas is between 0.5:1 and 1:10 . further comprising applying a second alternating current power to one of the one or more power electrodes of the substrate support, wherein the second alternating current power is applied per square centimeter of the substrate receiving surface of the substrate support. Or 0 . 14W and 7 . 1 W, the first AC power and the second AC power each have a frequency between 350 kHz and 100 MHz, and the frequency of the first AC power is equal to the frequency of the second AC power. 18. The method of claim 17 , wherein the frequency of alternating current power is different. A method of processing a substrate, the method comprising:
placing a substrate on a substrate support disposed within a processing volume of a processing chamber;
flowing a processing gas including a hydrocarbon gas and a diluent gas into the processing space;
maintaining the processing space at a processing pressure of less than 20 mTorr;
igniting and maintaining the process gas deposition plasma by applying a first alternating current power to one of the one or more power electrodes of the substrate support, wherein the first alternating current power is igniting and maintaining a deposition plasma of the process gas of between 0.7 and 15 watts per square centimeter of substrate receiving surface of the substrate support;
applying a second alternating current power to one of the one or more power electrodes of the substrate support, wherein the second alternating current power is applied per square centimeter of the substrate receiving surface of the substrate support; between 0.14 watts and 7.1 watts, the first alternating current power and the second alternating current power having frequencies between 350 kHz and 100 MHz, respectively; applying second alternating current power having a frequency different from the frequency of the second alternating current power;
maintaining the substrate support at a processing temperature of less than 100 degrees Celsius;
exposing a surface of the substrate to the deposition plasma; and
A method comprising depositing an amorphous carbon layer on the surface of the substrate. _The hydrocarbon _{gas is} CH4 _, C2H2 _{, C3H8} , C4H10 , _{C2H4 ,} C3H6 , _C4H8 , _{C5H10 ,} or a _combination thereof _. _ _ _{_} _ _ _{_} 20. A method according to any one of claims 17 to 19, comprising one of : 21. A method according to any one of claims 16 to 20, wherein the deposited amorphous carbon layer has a film stress of less than 500 MPa. 22. The method of claim 21, wherein the membrane stress is a tensile or compressive membrane stress. 23. The method according to any one of claims 1 to 22, wherein the treatment temperature is a subzero temperature of -50 degrees Celsius or higher. 5. The deposited amorphous carbon layer has a plurality of apertures formed through the layer, each of the plurality of apertures having a height to width ratio of greater than 2:1. The method according to any one of paragraphs 1 to 23. an amorphous carbon layer disposed on a surface of a substrate, the amorphous carbon layer comprising : 1 . Density greater than 8 g/cm ³ , Young's modulus greater than 50 GPa, film stress less than 500 MPa, and 0.5 g/cm 3 at a wavelength of 633 nm. A carbon hard mask having an absorption coefficient (optical K) of less than 15. 26. The carbon hard mask of claim 25, wherein the film stress is a tensile or compressive film stress. 25. The amorphous carbon layer has a plurality of apertures formed through the layer, each of the plurality of apertures having a height to width ratio of greater than 2 :1. or the carbon hard mask described in 26 . 28. The carbon hard mask of claim 27, wherein each of the plurality of openings has a height to width ratio greater than 10:1.

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